Latino gay/bisexual men constitute one of the most vulnerable groups in the nation for the transmission of HIV, showing some of the highest rates of seroprevalence, seroconversion, and unprotected anal intercourse with multiple partners. Preliminary studies suggest that sex under the influence of drugs is one of the strongest correlates of unprotected sexual practices, however, no study to date has directly focused on the use of drugs during sexual activity in this population. The overall goal of the proposed research program is thus to investigate the social contexts and individual patterns of drug use during sexual activity, as well as develop and test a theoretical model that explains the observed correlations between drug use and unprotected anal intercourse (risky sex) in Latino gay/bisexual men. We proposed to conduct three studies within a four-year period: Study 1 involves in-depth interviews with 90 men who report sex under the influence of drugs during the past two months, and who vary in age and degree of acculturation to the mainstream culture, including men from three identified high-risk groups: Homeless street youth; Male sex workers; and Transvestite/transgender individuals. Narrative data from in-depth interviews will be contextualized and triangulated through ethnographic observations of social contexts and venues that emerge as relevant and observable in the in-depth interviews. Study 2 involves close-ended interviews with 150 drug using Latino gay/bisexual men in order to construct a culturally appropriate and reliable instrument that measures quantitatively the explanatory variables in the relation between drug use and risky sex, as identified in Study 1. Study 3 involves a quantitative survey in a venue-based representative sample (N=400) of drug using Latino gay/bisexual men in order to asess frequency and mode of use for different types of drugs in the context of sexual activity, assess prevalence of drug abuse, risky sex, and their predictors, and test quantitatively the proposed theoretical model. The survey will be administered individually using the instrument developed in Study 2; survey participants will be recruited probabilistically, using the sampling frame and procedures developed in Study 1 and later refined and pilot tested in Study 2. A central aspect of the research program is to describe the social constructions and meaning assigned to different drugs regarding their perceived power to regulate and enhance sexual activity, and how drug use may be used as a socially shared and sanctioned justification of unprotected sexual activity in the population. We will explore the role of drug use in the sexual lives of Latino gay/bisexual men who differ in levels of acculturation to the mainstream (mostly White and middle-class) gay culture. In so doing, we will examine the contributions of cultured to the association between drug use and high risk sexual behavior, a perspective that has been neglected to date in the study of this relationship.